Ion source



May 20; 1958 G. A. BOUTRY ETAL ION SOURCE Filed May 17, 1955 INVENTORS G.A. BOUTRY G. PIETRI AGENT 2,s3s,s35

ioN sooner Application May 17, 1955, Serial No. 509,924

Claims priority, application France May 25, 1954 3 Claims. (Cl. 313--63) The invention relates to a source of ions, in which alkali metal ions or alkaline earth metal ions are produced on a heated anode.

A source of ions has been suggested, in which the ions are produced inside a heated anode space, which has an aperture leading to the discharge space. Via a further aperture the anode space communicates with a supply space, which is otherwise completely closed and which contains the alkali metal or alkaline earth metal. This supply space is at a lower temperature than the anode space, in which the ionisation of the vapour emanating from the supply space takes place at the surface. The anode space is heated by means of a heating Winding surrounding it.

The invention has for its object to provide a source of ions of simple construction, having a satisfactory output and a constant production.

In accordance with the invention, a source of ions, in which alkali metal ions or alkaline earth metal ions are produced on a heated anode and which comprises a supply space, which is closed with exception of one aperture, comprises an anode arranged inside the supply space in front of the aperture in the wall thereof in a manner such that the neutral vapour atoms can substantially not penetrate through or traverse the aperture without colliding at least once against the anode surface. It is thus ensured that substantially no neutral atoms can penetrate in to the discharge space, provided that the material of the anode and the temperature thereof are chosen correctly. For the production of cesium, rubidium, potassium, barium, sodium or lithium metal ions use may be made of an anode of platinum. For part of these metals use may otherwise be made of nickel, iron, carbon, molybdenum or tungsten.

The invention will be described more fully with reference to the accompanying drawing, in which Fig. 1 shows a diagrammatical sectional view of a discharge apparatus comprising a source of ions according to the invention and Fig. 2 shows part thereof on an enlarged scale.

The source of ions shown in Fig. 1 comprises a supply space 1, inside which provision is made of a supply 4 of the metal substance to be ionized. The supply space is closed by a metal diaphragm 3, which is sealed to the glass walls of the space 1. Near an aperture 2 in the rates Patent diaphragm 3 provision is made of a flat, anode 6 to be heated. The supply space 1 is surrounded by a heating wmding 5. On the other side of the diaphragm 3, inside a discharge space 7, provision is made of an 2,835,835 Patented May 26, 1%58 ICC accelerating electrode 9, an ion-optical system 10 and a collecting electrode 11. A load circuit (not shown) may be included in the lead to this collecting electrode.

Fig. 2 shows the position of the anode 6 relative to the aperture 2. Reference numerals 13 and 14 designate the paths of a few vaporized atoms travelling from the supply space 1 to the discharge space 7. Owing to the small distance between the anode 6 and the diaphragm 3 a collision with the anode will occur substantially always, and if the possibility of ionisation at the anode surface is substantially unity, the atoms will be completely ionized during this collision.

The anode 6 is constituted by a flat tape of tungsten or molybdenum, which is heated by passing current therethrough. The temperature of the anode is 750 C. to l000 C. The diameter of the aperture 2 of the diaphragm is l to 2 mms. The distance between the anode 6 and the diaphragm 3 is 0.3 mm. and the voltage of the anode relative to the diaphragm is 30 v.+. The apparatus described above may be used as a delay element in an electrical arrangement and as a source of ions for nuclear physics.

What is claimed is:

1. An ion source comprising an enclosure having walls and an aperture in a portion of a wall, an ion-producing substance within said enclosure, an anode member mounted in said enclosure at a position in proximity to but spaced from said aperture and preventing direct communication between the latter and said ion-producing substance, and means for heating the anode at a temperature at which particles of said substance impinging thereon are ionized, whereby unionized particles of said substance are prevented from traversing said aperture without impinging on said anode.

2. Anion source comprising an enclosure having walls and a single aperture in a wall at one end of said enclosure, an ion-producing substance selected from the group consisting of alkali and alkaline-earth metals disposed within said enclosure at an end remote from said one end, an anode member mounted within said enclosure in proximity to but spaced from said aperture and between the latter and the ion-producing substance, means for heating the ion-producing substance to generate unionized particles in said enclosure, and means for heating the anode at a temperature at which unionized particles of said substance impinging thereon are ionized, said anode member being located in a position at which said unionized particles cannot reach the aperture without first impinging on said heated anode.

3. An ion source as set forth in claim 2. wherein the anode is constituted of a metal, the heating means for said anode comprise means for passing electric current through said anode, and means are provided for maintaining the anode at a positive potential relative to the wall containing the aperture.

References Cited in the tile of this patent UNITED STATES PATENTS 2,078,112 Wologdin Apr. 20, 1934 2,499,289 Backus Feb. 28, 1950 2,697,169 Emslie Dec. 14, 1954 

2. AN ION SOURCE COMPRISING AN ENCLOSURE HAVING WALLS AND A SINGLE APERTURE IN A WALL AT ONE END OF SAID ENCLOSURE, AN ION-PRODUCING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE-EARTH METALS DISPOSED WITHIN SAID ENCLOSURE AT AN END REMOTE FROM SAID ONE END, AN ANODE MEMBER MOUNTED WITHIN SAID ENCLOSURE IN PROXIMITY TO BUT SPACED FROM SAID APERTURE AND BETWEEN THE LATTER AND THE ION-PRODUCING SUBSTANCE, MEANS FOR HEATING THE ION-PRODUCING SUBSTANCE TO GENERATE UNIONIZED PARTICLES IN SAID ENCLOSURE, AND MEANS FOR HEATING THE ANODE AT A TEMPERATURE AT WHICH UNIONIZED PARTICLES OF SAID SUBSTANCE IMPINGING THEREON ARE IONIZED, SAID ANODE MEMBER BEING LOCATED IN A POSITION AT WHICH SAID UNIONIZED PARTICLES CANNOT REACH THE APERATURE WITHOUT FIRST IMPINGING ON SAID HEATED ANODE. 